Microphone for telephonic instruments



July 6 1926. 1,591,066-

0. H.'WIGGIN$ MICROPHONE FOR TELEPHONIC INSTRUMENTS File 00? 1922 Esteem-Sheet 1 FIC l 1w VENTO DuDL 5) H. mad m A TTORNEYi July 6 1926. 1,591,066

D. H. WIGGINS rucnornonn FOR TELEPHONIC INSTRUMENTS File 1922 2 Sheets-Shoot 2 INVENTOR.

001.57 H. VV/GG/NSf.

A TTORNEYi hold the instrument.

Patented July 6,1926.

' DUDLEY HOWARD WIGGINS, OI INDIANAPOLIS, INDIANA.

MICROPHONE FOR TELEPHONIC INSTRUMENTS.

Application filed October 30, 1922. Serial 1T0. 597,834.

()ne objcct of this invention is to im prove transmitters for telephones of the microphone type and the like by making the same extremely sensitive and capable of 5 transmitting minor tones or overtones, as

well as major-or fundamental tones, whereby the tonesof the human voice and other tones will be more accurately, fully and naturally reproduced. It is well known that the ordinary microphones for telephones or the like are so made that they fail to transnnt or reproduce the minor tones and at the same time they relatively emphasize and magnify the major tones, so that there is relatively much noise and the minor tones are largely lost, and the timbre of the human voice or full quality of the tones is not reproduced. With this invention the minor tones are reproduced and the major tones not relatively exaggerated, but the human voice or other tones are received and transmitted so as to be perfectly natural and with all the original timbre and quality of tone. This is true not onl of tones from the human voice, but musical tones Where the minor tones and those which give richness and quality to the music are largely lost in ordinary microphones.

Another object of the invention is to enable one to talk into the microphone of a telephonic instrument without yelling or talking close to the microphone. \Vith this invention the tone will be full and clearly reproduced when the person talking through it is anywhere in the room. Mouthpieces are unnecessary and one is not required to transmitted when one is twenty feet away and with his back to the microp one.

* Another object of this invention is to provide a microphone for telephones and the like that can be enlarged to any size that mayv be required or esired for any use in any situation. In this invention the diaphragm construction is not limited to any it may be three feet in diameter, 'or'greater,

for receiving proceedings of conventions or large gatherings or orchestral music, or

The tones will be other complex and delicate sounds for radio broadcasting or any other purpose.

One feature of this invention consists in usmg a sheet of metal foil, preferably old foil, asthe diaphragm member, and w ich is not rigid or relatively stiff or resilient like the ordlnary diaphragm, which must be vlbrated as a unit, whether mounted at its margin tightly or loosely. The diaphragm in this invention is very thin and pliable and substantially non-resilient and arranged in connection with other parts of the transmitter so that it forms a considerable number of small similar sections, each of which is in the nature of a diaphragm acting by itself and without physically changing or affecting any other section or part of the total foil diaphragm member, although all the sectional diaphragms act synchronously and cumulatively to produce the full com-- plement of tones and the sectional dia- 1 phragms engage the same mass of carbon granules, minor as well as major tones. The ordinary transmitter diaphragm must be wholly or partially vibrated which can only be done by powerful sound waves. This is because of the'size and inertia of the diaphragm and consequently it is not much affected by the minor tones and is not at all affected by those tones which produce sound waves too weak to move the diaphragm. This kind of diaphragm also injures and confuses the reproduced tones because of the lag, due to the time required by the sound waves to move the entire diaphragm or overcome its inertia. The result is that the minor tones will not be synchronous with the overtones in the reproduction. In this invention the individual or-sectional diaphra m is so small and so thin and pliable that it is sensitive to slight sound waves, as the inertia is negligible, whereby. the waves from the minor tones can move it sutiiciently to be reproduced and without lag.

Another feature of this diaphragm construction is that it can be enlar ed to any extent without injuring its function, as the entire diaphragm member is not vibrated as a .whole, but is sectionalized into many small diaphragm sections which act independently of each other, but synchronously. Itis obvious, therefore, that the increase in size or number of sections or size as a whole will not reduce the sensitiveness or efiicacy of the transmitter, but will have the opposlte effect of making it a more powerful and sensitive transmitter because there is acting in unison many diaphragm sections. i

Another feature of the invention consists in the means of mounting said metal foil diaphragm so that it will perform its function as desired; This is accomplished by associatin it with a back non-conducting reticulate frame adjacent the granular carbon. The foil is held tightly against this frame so that the ortions of the foilin direct contact with t e frame do not vibrate, but only the intermediate surfaces of the foil vibrate and act as sectional or separate diaphragms. In addition, a similar reticulated frame, preferably a conductor, is placed in front of the foil so that the foil is practically clamped or held between these two frames which makes an easily made mounting of the foil and one which causes it. to operate successfully. i

Another feature of the invention is in adding, to the foregoing, means in the nature'of a layer of wood-like material in front of the foil or said front frame. Steel wool or other metallic wool in mass form is preferable for this purpose but any other kind .or resilient material having substantially the same irregular curl formation as the steel wool may be emp oyed so ion as it can be readily penetrated by the soun waves and yet not be responsive to them. This steel wool is held against the front electrode frame preferably by another wire screen in the front of the steel wool, so that the layer of fibrous material will be compressed into a fiat matlike character.

The full nature f the invention will be understood from t e accompanying 'drawings and the following description and claims. In the drawings, Fig. 1 is a front elevation of the transmitter. Fig. 2 is a central vertical section through the same. Fig. 3 is an elevation of a ortion of the chambered rubber frame for olding the granular carbon. Fig. 4 is a reproduction of a portion of what appears in Fig. 2 on a larger scale, showing the parts in normal position. Fig. 5 is the same showing the diaphragm member vibrated by a sound wave, the extent of vibration shown, however, being exaggerated for the sake of clearness. Fig. 6 is a section of part of one of the wire frames, and Fig. 7 is an elevation thereof.

There is shown in the drawings herein, for the purpose of illustrating the nature of the invention, a microphone or transmitter suitable for, and adapted to be mounted on, an ordinary telephone stand or otherwise. It is shown herein. however, somewhat enrecessed to receive the members or parts of the device which will hereafter be enumerated and these parts are held in the casing 10 by a retaining ring 15, made preferably of hard rubber, and secured to the fiber disk 13 by screws 16.' v l Within the cup-shaped disk 13 there is a carbon plate 17 and in front of it a reticulated or perforated rubber frame .18 to form pockets inwhich granular carbon 19 is placed. The carbon plate constitutes the rear electrode and is connected to the conduct-or 12 by a bindin post 20.

In front of the car on-holding frame 18 there is an insulated wire nettingor reticulated frame 21, extendin over the entire area of said frame 18. It is formed of cross wires which may be arranged about twelve to the inch each way for ordinary telephone use. It is preferably flattened by being run between a pair of strong'compressing rolls so as to make it thinner and have a smooth outer surface for the foil. It is japanned, or otherwise treated, to render it superficially non-conducting.

Against said reticulatedback frame 21 a sheet of metal foil 22 is placed orsecured- This is the diaphragm member in the device, but it is very thin and flexible, and referably non-elastic. It is preferably go (1 or gold plated foil, but other metallic foil may e used. The foil is held in place against the reticulated back frame 21 by a wire netting or reticulated frame 23 which is placed against the foil so that the latter is held tightly in place between said nettings 21 and 23. It is prefcrabl formed of the same size of wire as the netting frame 21, but preferably of copper wire or other good electrical conductor, and it is also preferabl rolled flat for the reason above specified. his conducting wire frame 23 is a part of the front electrode and in front of and against it there is a conducting ring 25 that extends all the way around and to it there is connected a copper strip 26 that runs throu h an opening in the isk 13 and back to a. inding post 27 for the wire 11.

In front of what maybe called the diaphragm construction, made of the foil and the two wire frames 21 and 23, there is placed a relatively thick mat or layer 28 of v wool-like material and it is retained by another wire frame v29 in front of it which is held in place by the retaining ring and so it will compress the wool-like material 28 and cause it to yieldingly hold the conducting wire frame 23 against the foil 22 and hold the foil securely against the rear wire frame 21 and hold said frame 21 against the carbon holding frame 18.

The Wool-like material 28 is preferably composed of steel wool, but it may be made of other wool or wool-like material. How- .ever, it is preferable and believed to be necessary to the successful operation of the device that this wool-like material be substantially resilient, elastic and so that it will frame, particularly if the wool-like material is moderately pressed against the diaphragm member. Also the alpparatus operates well if the rear reticu ated frame is not insulated, as some of the current still goes through the diaphragm to the carbon as heretofore described.

The foregoingdescription and the associated drawings explain substantially the general features and construction of this invention, although it is not limited to many of the articular details therein set forth. It is evident from what has been said that the gold foil or what may be termed the diaphragm will not vibrate as a whole and is so mounted and held that it is divided into a large number of relatively small diaphragm sections located substantially in the same plane. Each of these sectional portions of the foil is capable of vibration under the influence of the sound waves, as indicated by the arrow in Fi 4, and regardless of the other sections 0 the diaphragm. These sectional diaphragms are, therefore, very small and the foil very thin and pliable so that it is vibrated by a .very slight sound wave which renders it'extremely sen- .sitive. While a considerable bend is shown in the diaphragm in Fig. 5, that is an exaggeration, as the movement of the small is ver slight, entirely to scale in the drawings. Several small sectional diaphragms as explained are in engagement with the carbon granules in one com artment so that they engage the same bo y of carbon granules. V diaphragm does not have a body of carbon granules for itself alone. Very slight movements of the diaphragm cause it to engage some of the granular carbon and cause the same to operate in the usual manner in microphones. I y

By providing the transmitter with such Therefore each sectional) similar and sensitive diaphragm sections, it is enabled to be influenced by relatively slight sound waves and to transmit and reproduce the same, and since there is a large number of sectional diaphragms and they are substantially the same in size and character, their effect in reproducingthe sound is cumulative. That is, they act in the same way and at the same time and being distributed over a relatively considerable area, they more accurately reproduce the tones, especially those of the human voice and give to the reproducedtones the timbre and quality of the human voice; and since the minor tones arercproduced, the major tones are thereby relatively subordinated so that theyv are not so greatly emphasized as to cause a mere noise. In fact, it is the minor tones that enable different tones or sounds to be distinguished and the loud major tones that cause the confusion of sounds in'the ordinary telephone and which render it diflicult to distinguish the tones or sounds. Therefore, one of the important results of this transmitter is the purity of tone it causes to be reproduced.

One result, it is believed, of the large number of very small sectional diaphragms of similar character and action is the amplification by them of the very minor tones, whereby in the reproduced tones or sounds, they have the same relative strength or character that the major and stronger minor tones have in the original tones or sound. This amplification not only results from the multiplicity of the sectional diaphragnis, but from the free and sensitive movement of each smalldiaphragm because of the character of the diaphragm material. This result is i-m' possible where the diaphragm is made of a sheet of material that must be vibrated wholly or almost wholly and where there is much inertia and la The 'sensitiveness of the diaphragm in t is invention prevents lag in the minor. tones so that in the reproduced tones or sounds, the minor tones have the original position relative to the major tones in point of time as well as in strength.

Because of the sensitiveness of this instrument, it is unnecessary to have a mouthpiece or to be near the instrument and in practical use it does not have to be handled, but can be talked into from any part of the room and with ordinary tone of voice and when ones back is turned to it.

The nature and construction of this instrument enables it to be made of any size that may be required and desired for any use or situation. The ordinary transmitter cannot be made large because the diaphragm would become too heavy and the inertia thereof too great to be vibrated by. the ordinary sound waves. Since, however, in this instrument the small sections of the foil constitute a multiplicity of diaphragms and-they ment and adapt it for use in conventions and for reproducing distant and delicate tones and particularly in connection with radio telephoning and the like.

Another characteristic is that a very great energizing current may be used in connection with the instrun'ient without the hissing and sizzling noise heretofore associated with the use of large currents. This is not only of value in ordinary local telephoning, but particularly in long distance work and in radio telephony and the like.

By carbon holder is meant herein a holder for carbon granules.

The diaphragms in broadcasting radio devices are said to be stretched so taut that they are capable of vibrating with a greater frequency than the air waves that would come to it. In this invention, such high frequency is due to the smallness of the diaphragm or diaphragm section which enables it to vibrate at a greater frequency than the air waves that come to it. But in order to practically utilize such small diaphragm there must be a multiplicity of.them. in a transmitter acting independently and synchronously and 'as a unit. Hence the smallness of the diaphragm sections provides for the desired frequency of vibration and also renders them synchronous for if the diaphragm sections were large they would not act with perfect synchronism, especially for the air waves which are relatively weak and of high frequency.

The invention claimed is:

1. A microphone for telephonic instruments, including a multiplicity of independently and synchronously acting diaphragms located substantially in the same plane, and means for holding said diaphragms in engagement with a body of carbon granules.

2. A microphone for telephonic instruments, including a multiplicity of independently and synchronously acting diaphragms located substantially in the same plane, stationary means for engaging the margins of said diapliragms, and a body of carbon granules for engagement by said diaphragms.

3. A microphone for telephonic instruments, including a plurality of similar diaphr'agnrsections formed of relatively thin pliable metal sheet and located substantially in the same plane. stationary backing carrying the same, and a body of carbon. granules in engagement with said diaphragm sections.

4. A microphone for telephonic instruments, including a multiplicity of diaphragms. connected collectively in parallel capable of vibration independently of each other, stationary means for mounting the same which engages the margins of said diaphragms, and a body of carbon granules engaging the multiplicity of dia'phragms.

5. A microphone for telephonic instruments, including a multiplicity of independently-and synchronously acting diaphragms in parallel, a stationary frame which engages and holds the margins of said dia phragms, and a body of carbon granules in engagement with said diaphragms.

6: A microphone for telephonic instruments, including a diaphragm member formed of a relatively thin pliable metal sheet, means for holding it so as to sectionalize it into a plurality of independently and synchronously acting diaphragm sections, thesame body of carbon granules being in engagement with a number of said diaphragm sections. 7. A microphone for telephonic instruments, including a thin pliable metal sheet as the diaphragm member thereof, reticulated frames between and by which the diaphragm member is secured so as to sectionarlize it into a plurality of independently vi-v bratory and synchronously acting diaphragms.

8. A michrophone for telephonic instruments, as set forth in claim 7, with means for clamping together the margins of said diaphragm and reticulated frames, for the purpose stated.

9. A microphone for telephonic instruments as set forth in claim 7, and a carbon holder adjacent said diaphragm and one of the reticulated frames and provided with a plurality of chambers and granular carbon in said chambers, substantially as set forth.

10. A michrophone for telephonic instruments including a'thin pliable metal sheet as the diaphragm member thereof, a rear reticulated frame against which the diaphragm member is placed, a front reticulated frame for holding said diaphragm member against said rear frame so as to sectionalize the diaphragm member into a plurality of independently vibratory members, and av layer of wool-like material pressing against said front reticulated frame.

11. A transmitter for telephonic instruments, including a thin pliable metal sheet as the diaphragm member thereof, a rear reticulated frame against which the diaphragm member is placed, a front reticulated frame for holding said diaphragm member against said rear frame so as to sectionalize the diaphragm member into a plurali-- phragmmember is placed, a front reticulated frame for holding said diaphragm member against said rear frame so as to sectionalize the diaphragm member into a plurality of independently vibratory members, a layer of wool-like material placed against said front frame, and a reticulated frame in front of said wool-like material for pressing it against said parts to the rear thereof.

13. A microphone for telephonic instruments, including a carbon holder provided with a plurality of chambers, carbon granules in said chambers, a thin pliable metallic sheet as the diaphragm member, and means for holding said sheet in contact with.

the carbon granules in the chambers of the carbon holders and which sectionalizes said diaphragm sheet into a plurality of independently vibratory diaphragms in front of each carbon holding chamber;

14. A microphone for telephonic instruments including a carbon holder providing aplurality of chambers, granular carbon in said chambers, a reticulated frame coated with insulating material adjacent to said carbon holding frame, a. relatively thin flexible, non-elastic metallic sheet as the diaphragin member adapted to contact with said insulated reticulated frameand the gran- -ular carbon, and a reticulated frame made ed frame made of conducting material in front of and adjacent to said diaphragm member, a layer of yielding material adacent to sa1d conducting frame, a marginal front ring, and means for securing it to said rear disk so as to compress and hold the margins of said carbon holder, frames, dia phragm member and yielding layer together.

16. A microphone for telephonic instruments including a cup-shaped rear fiber disk, :1 carbon holder in front thereof providing a number of chambers, granular carbon in.

said chambers, a reticulated frame adjacent to said carbon holder and coated with noncon'dueting material, a relatively thin pliable .metallic sheet as the diaphragm member placed against said coated frame,1and-a. re-

ticulated frame made of conductin material in ,front of and adjacent to said laphragm member, a layer of yielding material adjacent to said conducting frame, amarginal front ring, a reticulated frame in front of said layer of'yielding material, a ring engaging the margm of sa1d last mentioned frame, and means for securing said ring to said cup-shaped rear disk so as to compress and hold together the margins of said carbon holder, frames, diaphragm member and layer of yielding material.

17. In a microphone for telephonic instruments, the combinationof a carbon electrode, a stationary and reticulated metal frame in front of said carbon electrode, said frame being insulated on the side thereof facing the carbon electrode, a diaphragm member adjacent the front side of said frame, granular carbon between the carbon electrode and said frame and 'diaphragm, and means for holding the diaphragm member against said frame so that the sections of the diaphragm member covering the openings in sa1d frame will be independently vibratory, substantially as set forth.

18. In a microphone for telephonic instruments, the combination of a carbon. electrode, a stationary and reticulated metal frame in front of said carbon electrode, said frame being insulated on the side thereof facing the carbon electrode, a diaphragm member adjacent the front side of said frame,-

granular carbon between the carbon electrode and said frame and diaphragm, and a con ducting ring for holding the margin of said diaphragm member tightly against said frame.

19. In a. microphone for telephonic in? struments, the combination of a carbon electrode, a stationary and reticulated metal frame in front of'said carbon electrode, said frame being insulated on the side thereof facing the carbon electrode, a diaphragm member adjacent the front side of said frame, granular carbon between the carbon electrode and said frame and diaphragm, a conducting ring for holding the margin of said diaphragm member tightly against said frame, and yielding means in front of. the diaphragm for yieldingly holding it against said metal frame and permitting the sections thereof covering the opening in said frame to be independently vibratory.

20. In a microphone for telephonic instruments, the combination of a carbon electrode, a stationary and recticulated metal frame in front of said carbon electrode, said frame being insulated on the side thereof facing the carbon electrode, a diaphragm member adjacent the front side of said frame, granular carbon between the carbon electrode and said frame and diaphragm, a conducting ring for holdin the margin of said diaphragm member tig tly against said all of said elements tightly together at their margin.

21. A microphone for telephonic instruments, including a thin pliable metal sheet as the diaphragm member thereof, a rear reticulated frame against which the diaphrng'm member is placed, a layer of wool- ]ike material in front of said diaphragm,

and means for pressing the wool-like material against the diaphragm member so, as to sectionalize it into a plurality of independently vibratory members.

my signature.

DUDLEY HOWARD WIGGINS. 

